1. Field of the Invention
The present invention relates to a device for safely introducing catheters into a blood vessel, organs, etc. with certainty.
2. Description of the Related Art
Upon introduction of catheters into the body for purposes of diagnosis or treatment, especially upon insertion of a vascular balloon catheter, a catheter for angiography or a catheter with a sensor for detecting temperature, pH, oxygen, etc. into a blood vessel, safe and sure handling is required
Seldinger's method has been widely adopted, as a method using a device as an auxiliary means for percutaneously introducing vascular catheters into a blood vessel. The basic technique of this method comprises percutaneously inserting a hollow stylus with an inner needle through the skin to thereby introduce the stylus into a blood vessel, withdrawing the inner needle from the hollow stylus, then inserting a guide wire into the hollow stylus, withdrawing the hollow stylus to keep the guide wire alone in the blood vessel, and then inserting into a blood vessel a catheter having an opening at the tip and the end, along the guide wire.
In addition, a method using an introducer for medical tube has also been widely used, by applying the basic technique of Seldinger's method described above. This method comprises first inserting a guide wire into a blood vessel according to the
Seldinger's method, next sliding an introducer coupled with a dilator into the blood vessel along the guide wire to keep the introducer in the blood vessel, and guiding the catheter along the guide path of the introducer thereby resulting in insertion of the catheter into the blood vessel.
The conventional prior art introduced as shown in FIG. 6A and B is constructed with a body (2), an end cap (43) and a valve means (64) composed of a resilient material to avoid bloodstream leaking. The catheter is slid and penetrated through body (2) of introducer (1) via valve means (64), whereby reflux or leakage of blood is prevented. However, when blood pressure is high for some reason or valve means (64) does not instantaneously close following sudden withdrawal of catheter (65), blood may leak out.
In the conventional prior art introducer, the dilator member is generally inserted and fitted into the inner cavity of a sheath member. However, stability in connection of the two members and operability has not been sufficient.
For example, in a medical device disclosed in Japanese Patent Application. No. 59-165452 (Japanese Patent Application Laid-Open No. 61-45774), as a means for preventing a relative motion in the dilator member and the sheath member, there is disclosed a structure in which only a concave portion and the convex portion are provided. Such a structure can prevent relative movement between both members in an axial direction and in a rotating direction but involves a drawback that stability in connection or operability is insufficient. That is, it is difficult to operate the dilator member when engaged to the sheath member because it is necessary to firmly hold the members which is a distraction during operation of the introducer. This is particularly a problem in catheterization while rotating a catheter or doing precise operations because so much attention must be directed to maintaining stability between the dilator and the sheath.
As described above, conventional catheter introducers involve complicated operations which require careful handling. Thus, there is a fear that trauma may occur upon insertion of a catheter into a blood vessel with prior art introducers.
In order to overcome these problems, prior art catheters such as shown in FIG. 7 have been developed in which a first valve member (76) is overlaid on a second valve member (77) to construct a valve means (64) and slits (62) provided respectively are in agreement at the central portion but other positions are staggered with each other thereby to enhance a liquid sealing effect around the dilator. This type of device is shown in
(Japanese Patent Application No. 58-196950 (Japanese Patent Application Laid-Open No. 60-88562), Japanese Patent Application No. 59-281077 (Japanese Patent Application Laid Open No. 61-154679) and Japanese Patent Application No. 59-90890 (Japanese Patent Application Laid-Open No. 60-234671).
When a catheter with a small diameter not closely fitted to a catheter tube is used or a guide wire alone is inserted with the prior art introducers, these devices are not always successful in preventing a reflux of blood-stream or leakage of blood. In addition, the valve members are merely overlaid on each other and not integrally joined and hence, a problem of stability between the dilator and the sheath is created.